1. Field of the Invention
This invention relates to communications between a terminal adaptor and terminal equipment and more particularly to reporting of error conditions.
2. Description of the Related Art
When Terminal Equipment (TE) such as computers, devices, application processors, wishes to access wireless services such as Third Generation Partnership Project (3GPP) services, the TE sends a request using attention (AT) commands to a terminal adaptor (TA). The TA includes circuits, such as in mobile devices that support 3GPP services.
Once the TE sends the request to the TA, the TA communicates with a 3GPP network to obtain services by, e.g., sending a service request to the network. Service requests can be accepted, rejected or even ignored by the network. Service requests can be denied by the network for a variety of reasons including network failure, network congestion, a user not being authorized for a requested service, or a user not being allowed to access the public land mobile network (PLMN).
When the service request is denied, the network sends a reject message which includes a reject/error code to the TA. Currently there is no good mechanism for the TA to forward this information to the TE. So in most cases the TE does not know the exact reason why the service requests fail. As the result, the TE cannot take appropriate action to recover from the failure. Lack of knowledge of the reason for the failure can lead to problematic TE behaviors. For example, if the TE fails in its attempt to access wireless service even though service is available, a had user experience can result leading to a potential loss of revenue for the carrier. If the TE keeps requesting the TA for service when service is not available, the repeated requests can lead to the battery draining very quickly and an excessive number of signaling messages being sent to network in a short period of time, which in the extreme case might bring the network down.
In the case of a service request being ignored by the network, the user equipment (UE) typically resends the request after a time-out period. In some cases, this resending of the service request can potentially continue indefinitely and may also result in an excessive number of requests being made to the network, which may impact the network adversely. In the case of these requests being ignored by the network, there is no defined mechanism for the TA to inform the TE of this condition.